One could have been forgiven for assuming that, in the course of four and a half hours of combined presidential debates, all policy bases would have been covered.

Big Bird, binders full of women and battleships all featured, after all.

But a surprising number of major issues failed to warrant a mention in any of the three head-to-heads. Here's a guide to what was not discussed – and the candidates' stances on the forgotten topics.

Gay rights

Despite Obama making a high-profile U-turn on the issue of gay marriage just months ago, the topic of same-sex unions didn't get a look in. The closest Obama got to an attack was a snide jab at Romney getting his social policies from the "1950s".

Where they stand:

Obama: Has pushed through a progressive agenda in terms of gay rights, having jettisoned the "don't ask don't tell" policy of previous administrations. His conversion to being pro same-sex marriage has been welcomed by the LGBT community, as has his direction to government bodies not to defend the Defence of Marriage Act (Doma) in the courts.

Romney: His agenda of gay rights has been built on shifting sands over the years. In the mid-1990s he told Log Cabin Republicans that he supported "full equality for America's gay and lesbian citizens". But he has veered towards social conservatism over the last year, repeatedly asserting his belief that "marriage is between a man and a woman". He has said he will defend Doma.

War on drugs

America's war on drugs could have been brought up in the debate on domestic agenda or in the foreign policy encounter.

But despite absorbing massive federal funds – some $51bn annually, according to the Drug Policy Alliance – no mention was made of America's longest war.

Where they stand:

Obama: The White House has failed to scale down the expensive enforcement-based approach on drugs legislation. Obama has also come out against legalisation. He did, however, bring in legislation to reduce the disparity between sentences given to those caught with crack cocaine, compared to users of powder cocaine. He has also diverted more funds to prevention and treatment programmes.

Romney: Likewise anti-legalisation, Romney blames demand in the US for the cross-border violence in Mexico. In a recent forum organised by the Univision TV Network, the Republican reportedly said that the US president has to make "a priority of reducing demand in this country and communicating to our young people, and older people, that when they use these illegal drugs, they are contributing to the deaths of people around the world".

Climate change

In the course of the presidential debates, the topics of gas prices and energy independence came up. But neither candidate turned the issue around to green energy and the issue of climate change.

Where they stand:

Obama: Has pledged to reduce emissions which cause global warming and hit out at sceptics, warning at the Democratic national convention: "Climate change is not a hoax." Obama has also pumped money into the green sector through government grants and loans.

Romney: Has called for the phasing out of subsidies for the wind industry and has mocked Obama for wanting to help "heal the planet". Although not an outright denier, Romney has said that we "do not know what's causing climate change on this planet".

Domestic surveillance

Discussion on homeland security during the first debate failed to nail the candidates on creeping surveillance of US citizens.

Where they stand:

Obama: According to the American Civil Liberties Union there has been a 60% increase in electronic surveillance under Obama's watch. He also extended the controversial patriot act, with authorises the wiretapping of US and non-US citizens.

Housing

With the economy very much central in the election campaign, it is surprising that some of the main victims of the recession – homeowners left underwater by falling house prices and those foreclosed on – didn't get a look in.

Where they stand:

Obama: Has introduced legislation that has helped millions of struggling homeowners, but not as many as he would have hoped. The home affordable modification programme has helped an estimated 1 million families refinance their home loans, but it's goal was to help up to 4 million.

Romney: Has criticised attempts to interfere with the housing market. Indeed his free-market approach appears to extend to giving no help to those facing repossession. "Don't try to stop the foreclosure process. Let it run its course and hit the bottom," he said in reference to housing.

Abortion

The issue came up in the vice-presidential debates, but despite both presidential candidates looking to secure a larger chunk of the female vote, abortion made no impact on their encounters.

Where they stand:

Obama: Is pro-choice. "I remain committed to protecting a woman's right to choose and this fundamental constitutional right," Obama said in January, ahead of the 39th anniversary of Roe v Wade.

Romney: Has flip-flopped on the issue over the years but now says he is opposed to abortion, except in the case of incest, rape and if the mother's life is endangered.